1. Field of the Invention
The present invention is related to a plastic grinding method under isostatic pressure, and especially to a method which can be used for grinding workpieces made of harder metal or alloy with three dimentional shapes, wherein, it includes using of a container capable of bearing high pressure and of generating vibration with supersonic waves, work-pieces to be ground and grinding granules and a grinding compound required are placed in the container, then increase the liquid pressure of the grinding compound to a predetermined value, so that a thrust function of isostatic pressure can be applied to the surfaces of the workpieces (the Pascal's law) from the grinding granules activated by the grinding compound, together with the additional function of vibration with supersonic waves generated in the container, stress on the surfaces of the workpieces made of metal or alloy bearing the isostatic pressure function are much reduced (Blaha effect), then the grinding compound and the grinding granules have a better result of grinding on the workpieces under the isostatic pressure circumstance and the Cavitation effect formed by the vibration with supersonic waves.
2. Description of the Prior Art
A conventional processing technique of polishing by fine cutting on a work-piece by using the vibrational grinding technique has been known for long, wherein, a liquid grinding compound and grinding granules are placed in a grinding chamber of a grinding machine, by a vibrating motor having a biasing weight, it can generate a vibration force in a predetermined angle, and thereby can make the grinding compound and grinding granules create disturbing collision styled grinding cutting action on the work-piece to be ground, so that the surfaces of the work-piece are smoothened, and the object of polishing can be achieved.
However, in the above stated conventional vibrational grinding technique, a technique of allocation for getting the angular scope of vibration of the vibration motor is very important, a good design can get a three dimensional turbulent vortex styled collision grinding and grinding effect among the work-piece, the grinding compound and the grinding granules in the grinding chamber, and hence quality of the work-piece can be largely improved.
There is still a technical impedance which has been being difficult to be overcome even when using the most well-done three dimensional vibrational grinding technique, this is because even the most well-done three dimensional vibrational grinding technique can hardly perform grinding and polishing on a work-piece having an small hole or fine slit; and it is difficult to keep the original sharpness of angles and edges in getting the smoothness after grinding of the whole three dimensional walls on a coarse blank made of metal or alloy with higher hardness or the work-piece having angles and edges; and even more, it is very difficult to use the vibrational grinding technique for grinding and polishing the work-pieces having more complicated three dimensional contours (those having undulated surfaces) in mass production, this is also a well known technical impedance in the art.
The largest problems making the conventional three dimensional vibrational grinding technique difficult in grinding the work-pieces having small holes or fine slits or the work-pieces having more complicated three dimensional contours does not exist in selection of the material of the grinding compounds and the grinding granules, in fact, it exists in the phenomenon wherein disturbant collision with unequal pressure is generated among the work-pieces to be ground three dimensionally and the grinding granules and the grinding compounds, this phenomenon is used to create tangential collision between the work-pieces to be ground and the grinding granules via the grinding compounds, so that the effect of grinding and cutting can be achieved; However, it is known that, in a circumstance with unequal pressure, tangential disturbant grinding and cutting can hardly get the grinding granules into the small holes and fine slits to form tangential grinding action, i.e., the axle holes and the fine slits are lack of enough space for the collision styled grinding cutting with tangential grinding action, and this is the primary cause why the conventional three dimensional vibrational grinding technique is difficult in grinding and polishing the work-pieces having axle holes or fine slits or the work-pieces having more complicated three dimensional contours. Further, vibrational grinding with tangential grinding action often hurt the areas having sharp angles or edges by collision or striking, this is also a large problem; And more, work-pieces made of metal or alloy with overly high hardness ground in vibration with tangential grinding action under a non equalized pressure circumstance may have the trouble of having a seriously insufficient frictional coefficient, this is not economic.